The present invention relates to a laminate, a barrier film and a manufacturing method thereof.
A method for forming thin films on a surface of material includes CVD (Chemical Vapor Deposition) and PVD (Physical Vapor Deposition), in which vapor allows substances to move at an atomic level or molecular level like a gas.
As a typical PVD method, a vacuum evaporation method or a sputtering method has been employed. Specifically, in the sputtering method, generally, even though the apparatus is costly, high quality thin films can be formed with film properties including excellent uniformity and film thickness. Hence, the sputtering method has been widely used for liquid crystal display devices and display devices.
Meanwhile, in the CVD method, raw material gas is introduced in the vacuum chamber and one or two or more types of gasses are decomposed or reacted on the substrate by thermal energy so as to grow a solid thin film. When decomposing or reacting gasses, to accelerate the reaction during the film formation or to lower the reaction temperature, a plasma or a catalyst reaction may additionally be used, which are referred to as PECD (Plasma Enhanced CVD) and Cat-CVD respectively. Such CVD methods produce fewer defects during the film formation and are mainly used for manufacturing processes of semiconductor devices, for example, a film-forming process of the gate insulation layers.
In recent years, an ALD method (Atomic Layer Deposition) is attracting attention. The ALD method is a method in which surface-adsorbed material is formed at an atomic level, layer by layer by a chemical reaction on the surface thereof, and is categorized as a CVD method. The ALD method is distinguished from a general CVD method. In a so-called CVD method (general CVD method), a thin film is grown by a reaction on the substrate by using a single gas or plural gasses. In contrast, the ALD method is a specific method, that is, the ALD method uses highly active gas such as a precursor (TMA: Tri-Methyl Aluminium) and a reactive gas (also referred to as a precursor in the ALD method) alternately, and by using surface-adsorption on the substrate and the subsequent chemical reaction, a thin film is grown at an atomic level layer by layer.
As a disadvantages of the ALD method, to perform the ALD method, specific material has to be used, which causes an increase of cost. Further, perhaps the greatest disadvantage is that a rate of film-formation is low. For example, compared to a regular vacuum evaporation method or a regular sputtering method, the rate of film-formation is 5 to 10 times lower.
To obtain excellent films by using the ALD method, it is important to try to improve processes of the ALD method and also a pre-process of the ALD method (for example, refer to patent literature 1: PTL1). PTL 1 discloses a technique in which a plasma treatment is applied to an insulation layer on a semiconductor substrate thereby improving step coverage of a film formed by the subsequent ALD method.
As a related art, a technique is disclosed in which atomic layer deposition is performed so as to form a gas-permeable barrier layer on a plastic substrate or a glass substrate (For example, refer to patent literature 2: PTL 2). In PTL 2, a light-emitting polymer is mounted on a plastic substrate having optical transparency and an atomic layer deposition is performed on a top surface and a side surface of the light-emitting polymer by the ALD method (i.e., a top coating is applied). Thus, a technique achieving a barrier film having optical transparency is disclosed in which coating defects can be reduced and gas permeation through several dozens of nanometer of thickness can be remarkably reduced.